Construction related to the supply pipe for pulp in the headbox of a paper machine

Abstract: The invention concerns a construction related to the supply pipe (S₁) for pulp in the headbox of a paper machine, by means of which construction any movements taking place during tilting of the headbox are compensated for and transfer of strains to the stationary supply pipe (S₂) is prevented. The movement compensator (10) comprises a first pipe (11), which is connected to the supply pipe (S₁) by means of a connecting flange (12) that permits rotation, and a second pipe (13), which is connected to the first pipe by means of a connecting flange (14) that permits rotation and which second pipe is further connected to the stationary supply pipe (S₂) by means of a connecting flange (15) that permits rotation.

Description: The invention concerns a construction related to a supply pipe arrangement for pulp at the inlet header of a tiltable headbox of a paper machine, more specifically an arrangement according to the preamble of claim 1, which is based on CH-A-393 068. When the headbox of a paper machine is being tilted, the supply pipe is provided with means of equipment that permit rotation of the supply pipe. It has been known from prior art to manufacture at least a portion of the supply pipe out of an elastic material which permits rotation of the supply pipe while the opposite end of the elastic construction remains stationary. A drawback of said construction is the poor strength of the material. During tilting of the headbox, the end connected with the headbox has moved along a relatively wide path while the opposite end of the supply pipe has remained stationary. The material is subjected to a high torsional strain, as a result of which the service life of the pipe has become limited. This problem has been solved by the characterizing features of claim 1. Preferred embodiments are defined in claims 2-7. Thus, according to the invention, it has been realized to form a joint construction that permits a tilting movement of the headbox, i.e. a movement compensator, in the pulp supply pipe of the headbox, which joint construction comprises a first pipe, which is linked and placed in an oblique angle in relation to the header so that it permits rotation. In the construction, the first pipe of the movement compensator is connected with a second pipe, which is installed at an oblique angle in relation to the first pipe of the movement compensator. The first pipe of the compensator is linked by means of a flange joint that permits rotation in relation to the feed pipe and, in a corresponding way, the first pipe is linked by means of a similar flange joint that permits rotation in relation to the second pipe of the compensator. In a corresponding way, the second pipe of the compensator is linked by means of a flange joint so that it can rotate in relation to the pulp supply pipe placed in a stationary position. When the headbox of the paper machine is pivoted around the pivot shaft, the movement compensator in accordance with the invention permits said pivoting. The mechanism in accordance with the invention, which is a sort of an articulated crank mechanism, permits shifting of the headbox both in the y-direction and in the z-direction (FIG. 1). Thus, pivoting of the headbox produces no strains in the stationary pulp supply pipe. Also, the running of the flow of the pulp through said compensator is smooth, because the pipe arrangement of the compensator does not produce major directional changes in the running of the pulp flow. In practice, the difference in height between the centre line of the supply pipe and the end of the first pipe of the compensator is 30 mm and, in a corresponding way, the distance between the end of the first pipe and the central axis of the pulp feed pipe is 30 mm. The invention will be described in the following with reference to some preferred embodiments illustrated in the figures in the accompanying drawing, the invention being, however, not supposed to be confined to said embodiments alone. Figure 1 is a side view of the headbox of a paper machine. Figure 2A shows a movement compensator in accordance with the invention as installed in the supply pipe connected with the pulp-flow header. The solution of equipment is shown as viewed in the direction K, indicated in Fig. 1. Figure 2B shows the construction as viewed in the direction of the arrow K 2 indicated in Fig. 2A. Figure 2C is an axonometric illustration of the geometry of the movement compensator. Figure 2D shows the geometry of Fig. 2C as viewed in the direction of the arrow K 3 . Figure 3 is a sectional view taken along the line I-I in Fig. 2A. Figure 4 is a side view of the flange construction as viewed in the direction of the arrow K 4 in Fig. 3 and partly in section. Figure 5 is an enlarged illustration of the area A in Fig. 4. Fig. 1 is a side view of the headbox of a paper machine. The headbox of the paper machine can be tilted by means of an actuator T. The geometric pivot axis of the headbox of the paper machine at the bracket C is, in Fig. 1, denoted with the letter X. The inlet header of the headbox P of the paper machine is connected with a paper-pulp supply pipe S 1 . As an articulation structure that permits rotation of the pipe S 1 , the supply pipe S 1 comprises a movement compensator 10, by whose means the supply pipe S 1 is connected with the intake pipe S 2 . Figs. 2A and 2B show the supply pipe S 1 , which is connected to the headbox P of the paper machine and which is also connected with the stationary pulp supply pipe S 2 by means of the compensator 10 which permits movement of the pipe S 1 . The geometric central axis of the supply pipe S 1 is denoted with X'. In a corresponding way, the central axis of the stationary pulp supply pipe S 2 is denoted with X". The movement compensator 10 in accordance with the invention comprises a first pipe 11, which is linked with the supply pipe S 1 by means of an articulated connecting flange 12 that permits rotation. The first pipe 11 is mounted so that its central axis X 1 is placed at an oblique angle (α) in relation to the central axis X' of the supply pipe S 1 . The connecting pipe 11 is connected with the second pipe 13 by means of a connecting flange 14 which permits rotation of the pipes 11,13. The second pipe 13 is passed in a direction inclined (angle β) in relation to the first pipe 11 and to its central axis X 1 and connected to the stationary pulp supply pipe S 2 by means of a connecting flange 15 so that rotation is permitted. Fig. 2C illustrates the movement geometry of the compensator. According to the invention, the movement compensator is composed of a pipe construction connected with the supply pipe S 1 and with the stationary pulp supply pipe S 2 . The compensator 10 comprises a first pipe 11 and a second pipe 13. Between the first pipe 11 and the second pipe 13, there is a flange joint 14 that permits rotation of the pipes in relation to one another. In a corresponding way, between the first pipe 11 and the supply pipe S 1 , there is a flange joint 12 that permits rotation, and between the second pipe 13 and the supply pipe S 2 , there is a flange joint 15 that permits rotation. The common plane of the central axis X' of the supply pipe S 1 and of the central axis X 1 of the first pipe 11 of the compensator 10 is denoted with T 1 . In Fig. 2C, the plane that is perpendicular to the plane T 1 and in which plane the central axis X' of the supply pipe S 1 is placed is denoted with T 2 . In the construction in accordance with the invention, the second pipe 13 of the compensator is placed in the plane T 3 , which is parallel to the plane T 2 . By means of an arrangement in accordance with the invention, tilting of the headbox and, thus, shifting of the supply pipe S 1 both in the direction Y and in the direction Z (in Fig. 1) are permitted. Fig. 2D shows the arrangement of equipment as viewed in the direction of the arrow K 3 in Fig. 2C. The figure shows the end points B 1 ,B 2 and B 3 of the central axes of the pipes S 1 ,11 and 13 as viewed in the direction K 3 . In the way shown in the figure, the distance L 1 between B 1 and B 2 is about 30 mm, and in a corresponding way the distance L 2 between B 2 and B 3 is also about 30 mm. When the compensator is placed in its position in connection with the supply pipe S 1 and S 2 , the pipe 11 i preferably placed so that the plane T, intersects the pivot axis X of tilting of the headbox P. In the solution, in such a case, both the central axis X' of the supply pipe S 1 and the central axis X" of the stationary supply pipe S 2 can be kept on the same line in the vertical plane and so that there is just the above difference in height of 30 mm between them. Fig. 3 shows the connecting flange construction as a sectional view taken along the line I-I in Fig. 2A. The connecting flange construction 14 comprises a joint collar 16, which is fitted to be openable and which is fitted to consist of two sides, comprising collar halves 16a,16b, which are linked with each other at the articulation points 17. The collar halves 16a, 16b of the joint collar are joined together by means of a screw 18, which is passed through the brackets provided on the collar parts. Fig. 4 shows the flange construction as viewed in the direction of the arrow K 4 in Fig. 3, i.e. as a side view and partly in section. Fig. 5 shows the area A of Fig. 4 on an enlarged scale, i.e. the joint flange construction 14. The pipe 11 of the compensator is provided with an end portion G, which is provided with a shoulder and a flow opening, and, in a corresponding way, the second pipe 13 is provided with an end portion G 2 which is provided with a shoulder and a flow opening. The side faces E 1 and E 2 of the end portions G 1 , G 2 with shoulders are placed at an oblique angle in relation to the radius R, of the joint, in which case, by turning the screw 18, it is possible to regulate the force with which the pipes 11,13 are pressed against one another. The tightening force is chosen so that rotation of the pipe 11 in relation to the pipe 13 is permitted. The side faces are jointly operative, with a wedge effect, with the side faces U 1 and U 2 of the groove U in the collar. The joint collar 16 comprises a groove U section whose form corresponds to the outer shape of the shoulders G 1 , G 2 . When the collar 16 halves 16a, 16b are joined together by means of the screw 18, the pipe portions 11,13 to be joined together are pressed against one another and kept together. The pipe 11, which is provided with the end shoulder G 1 , comprises a groove V in the front face N 1 of the shoulder G 1 , into which groove V the shoulder end G 2 of the pipe portion 13 to be connected with it can be placed so that the front-face shoulder D placed on the front face N 2 of the shoulder end is placed into the groove V. The figure shows the area A in Fig. 4, i.e. the connecting flange 14 between the pipes 11 and 13. A construction similar to that described in relation to Fig. 5 is also provided between the pipe 11 and the supply pipe S 1 , i.e. the connecting flange construction 12 is similar to the connecting flange construction 14. In a corresponding way, between the pipe 13 and the stationary supply pipe S 2 , there is a construction similar to that between the pipe 11 and the pipe 13, i.e. the connecting flange construction 15 is similar to the connecting flange constructions 14 and 12. Thus, in the figure, just one of said connecting flange constructions is illustrated by way of example, i.e. the connecting flange construction 14 between the compensator pipes 11 and 13.

Claims: Supply pipe arrangement for pulp in a tiltable headbox of a paper machine, one end pipe (S 1 ) of which arrangement (S 1 , 11, 13, S 2 ) being directly connected to the headbox and the other, remote end pipe (S 2 ) of which being stationary with respect to the headbox (P), wherein the arrangement includes a movement compensator (10), by means of which any movements taking place during tilting of the headbox are compensated for and transfer of strains to said stationary remote end pipe (S 2 ) is prevented, characterized in that the movement compensator (10) comprises a first pipe (11), which is connected to said one end pipe (S 1 ) by means of a connecting flange (12) that permits rotation of the first pipe (11) with respect to said one end pipe (S 1 ), and a second pipe (13), which is connected to said first pipe (11) by means of a connecting flange (14) that permits rotation of the second pipe (13) with respect to the first pipe (11) and which second pipe is further connected to said stationary end pipe (S 2 ) by means of a connecting flange (15) that permits rotation of the second pipe (13) with respect to the stationary end pipe (S 2 ). Supply pipe arrangements as claimed in claim 1, characterized in that the first pipe (11) is installed at an oblique angle in relation to the central axis (X') of said one end pipe (S 1 ) and that the second pipe (13) is installed so that its central axis (X 2 ) is placed at an oblique angle in relation to the central axis (X 1 ) of the first pipe (11). Supply pipe arrangements as claimed in claim 2, characterized in that the second pipe (13) is installed in a first plane (T 3 ) at an oblique angle in relation to the central axis (X 1 ) of the first pipe (11), which first plane (T 3 ) is parallel to a second plane (T 2 ) which has been drawn as perpendicular to the common plane (T 1 ) of the central axis (X') of said one end pipe (S 1 ) and of the central axis (X 1 ) of the first pipe (11) and which second plane (T 2 ) runs through the central axis (X') of said one end pipe (S 1 ). Supply pipe arrangements as claimed in any of the preceding claims, characterized in that said three connecting flanges (12,14,15) comprise an end portion (G 1 ) that is provided with a shoulder and that is included in a pipe or end pipe (S 1 ,11,13) an end portion (G 2 ) that is provided with a shoulder and that is included in the other pipe or end pipe (11,13,S 2 ) to be joined, said shoulders (G 1 ,G 2 ) being joined together by means of a joint collar (16), which comprises a groove (U) and therein a cross-sectional shape that is compatible with the shapes of the shoulders (G 1 ,G 2 ). Supply pipe arrangements as claimed in the preceding claim, characterized in that the joint collar (16) comprises collar halves (16a,16b), which are joined together by means of a screw (18), in which case, by regulating the tensioning force of the screw (18), the force is regulated with which the shoulders (G 1 ,G 2 ) are pressed against one another, the tensioning being, however, such that rotation of the interconnected pipes/end pipes in relation to one another is permitted. Supply pipe arrangements as claimed in claim 5, characterized in that the outer side faces (E 1 ,E 2 ) of the shoulders (G 1 ,G 2 ) are placed at an oblique angle in relation to the direction of the radius (R 1 ) of the joint, in which case, by turning the screw (18), it is possible to regulate the force with which the pipes/end pipes are pressed against one another while the side faces (E 1 ,E 2 ) of the shoulders (G 1 ,G 2 ) are jointly operative, with a wedge effect, with the cross-sectional shape of the groove (U) in the joint collar. Supply pipe arrangements as claimed in any of the claims 4-6, characterized in that the end shoulder (G 1 ) of the first pipe (11) comprises a groove (V) in its front face (N 1 ), into which groove the shoulder end (G 2 ) of the second pipe (13) to be connected can be placed so that the front-face shoulder (D) provided on the front face (N 2 ) of the shoulder end (G 2 ) of the second pipe (13) is placed into the groove (V).

Inventors: PITKAEJAERVI KARI, PITKAEJAERVI, KARI, Pitkäjärvi, Kari
Applicants: VALMET CORP, VALMET CORPORATION
Application year: 1994
Main classification: D21F1
IPC codes: D21F1, F16L27